How to get the store directory of a package output?

[Jan Nieuwenhuizen]

Hi!

Using #$icedtea-8 inside a gexp gives me the store directory of the
default icedtea's output.  Adding (string-append #$icedtea-8 "/bin")
to PATH gives me java.

How do i get to the bin directory of javac, i.e. the "jdk" output of
icedtea-8 inside a gexp?

Greetings,
janneke